Co-based alloy coating is prepared on the sealing surface of the seat made by 410-stainless steel. Effects of different Co-based powder and different process parameters and the subsequent heat treatment on the variation of formability and properties of the cladding coatings are analyzed by metallographic analysis, hardness testing and scanning electron microscopy. The result shows that the powder prepared by A and C has has good moldability, and with the increase of scanning speed, the width of the cladding layer decreases, the hardness increases, the cladding cracks tend to increase. The effects of the heat treatment on the hardness of the cladding coating is not obvious, but it can It can significantly reduce the hardness of the HAZ. The optimum technology is laser power 3.5 kW, scanning speed 100～150 mm/min, the mixtured powder of A and C was prepared for coating by laser cladding, then take the tempering on the cladding coating. We can get the cladding coating meet the requirement on the 410-stainless steel.

With the preset powder, Fe-based amorphous composite coating was prepared by laser cladding on 700 MPa steel. The effects of laser scanning speed and laser power were studied on micro-hardness of laser cladding layer, which shows that a proper scanning speed and 1.5 kW of laser power will be better for getting higher micro-hardness of laser cladding layer. At the same time, the influence of micro-alloy element Nb and Nitrogen content were studied on the micro-hardness of laser cladding layer.

TC4( Ti-6Al-4V) titanium alloys exhibit a remarkable combination of high specific strength and good oxidation resistance, which make them useful for aerospace and chemical industrial applications. However, they suffer from low wear resistance, which limits them in applications where abrasive or erosion phenomena are present. Over the last decade, various types of surface modification techniques have been developed aimed at improving the wear resistance of Ti and its alloys. Among the various surface engineering methods, laser surface nitriding is a promising method. In present paper, laser surface nit riding is carried out on the surface of TC4 alloy by Nd:YAG laser in a mixture of nitrogen and argon gases with different ratio. The influence of N2 ration on the microstructure and hardness is investigated．The results show that the nitriding zone is divided into three layers, i.e, melting zone, heat affected zone and base material. Melting zone consists of TiN in a form of dendrites. Dendrite consists of orientated growth columnar grains at the bottom, with a small dendrite dendrites existed in the form of needle-like. There are obvious micro-cracks in the melting zone, which caused by thermal stress. The stress is the result of the surface rapid melting by the laser pulse, and then solidification quenching. The microhardness of the nitriding is approximately 600～800 HV, which is 2 times of the TC4 substrate.

Titanium alloy has high strength, low density, high corrosion resistance, which are being used in aerospace and chemical industries. But its low wear resistance restricts wider application. In the paper, the laser treated and untreated samples of TB5 alloys are placed in a special solid medium for oxygen diffusion. By studying the furnace heating conditions and the pretreatment process, an analysis is performed on the microstructure and hardness of TB5 alloys. What’s more, we make a comparison between TB5 and TA4 titanium alloys under the same experimental conditions. The experimental results indicated: Under the same temperature and time a hardened layer is formed on the surface of the laser treated and as-received samples. The thickness and hardness of the oxygen-diffusion zone formed on the laser treated sample are much higher than that of the as-received sample. Under the same experimental conditions, TA4 titanium samples are easier for oxygen diffusion, compared with TB5 titanium alloys.

The hard particles reinforced intermetallic composite coating was fabricated on biomedical TC4 titanium alloy by laser cladding process in this paper. The microstructure, phase structure and composition, distribution of hardness and corrosion resistance of the hard particles reinforced intermetallic composite coating were analysed by optical microscopy(OM), scan electron microscopy (SEM), Energy spectrum (EDS) quantitative analysis, X-ray diffraction (XRD) and polarization curve. The results show that the coating thickness up to 1~2 mm, and sufficiently dense, uniform, crack-free, and without porosity defects, the phase compositions of the coating including hard particles additonal B4C、in-situ synthesis TiB、TiB2 and TiC、TiNi/Ti2Ni dual phase intermetallic composite. The hardness of hard particles reinforced intermetallic composite coating is HV 0.3 899, nearly 3 times of the substrate, and the corrosion resistance of the coating is nearly 3 times of the substrate.

The elastic elements manufactured by different treatment processes were treated by laser shock processing (LSP) with high power Nd:YAG laser. Residual stresses on inner surface were measured by X-ray diffraction (XRD) and principal stresses were calculated. The relationship between residual stress and residual principal stress was analyzed, and the influence of LSP on the elastic element fatigue source was discussed. The results indicate that residual compressive stresses on surface of springs were obtained. The quantitative relation exists between principal stress and residual stress. To prevent the crack expansion, the direction of residual maximum principal stress was changed and the residual stress at 0° was controlled.

Dissimilar joining of lapped E36 steel plates to aluminum alloy 5083 sheets was carried out by using laser keyhole welding process with the addition of Ni, Zn and Sn filler powders. By using optical microscopy, scanning electron microscopy, energy disperse spectroscopy, the microstructures and microscopic hardness of the welded joints with the filler powders were studied. The results show that the addition of powders into the weld joint can improve the morphology of the intermetallic compound (IMC), reduce the thickness of Fe-Al IMC, and finally improve the ductility and toughness of the weld joints.

In this essay, the experimental material is 5.0 mm thick high strength steel plate, and analyzes the weld shaping, droplets transfer characteristics and melt flow on impurity distribution of hybrid welding processes of CO2 laser-MAG hybrid welding with different the distance between laser and arc. Experimental results show that: the effect of two heat sources interaction effect is changed with different distance with laser and arc. When the distance is 4 mm,the frequency of the droplet transfer is the maximun and the weld shaping is more smooth. The crystallization process of the molten pool accompanied by the liquid metal flow. And the influence of the liquid metal flow is very important to melt flow on impurity distribution. When DLA＝3 mm and the distance to molten pool surface is 1.0 mm the adding elements in the molten pool content is higher and its distribution is the most uniform.

The laser keyhole welding was carried out onthe butt joints between the Q235 steel sheets with thickness of 3.5 mm and the 6.0 mm thick 5083 aluminum alloy with a fiber laser. The effects of laser distance on the weld shape were investigated. The microstructures and mechanical properties of the joints were investigated by optical microscope, scanning electron microscope,micro-hardness tester and tensile testing machine. Results show that the thickness of intermetallic layer in the interface of the welded joints gradually decreases from 21.0 μm to 4.1 μm with laser distance varies from 0.3 to 0.7mm. When the laser distanceis 0.7 mm and 0.3 mm,the average hardness of the intermetallic layeris 765.4 HV and 671.3 HV, respectively. The maximum tensile strength is 107 MPa when the laser distance is 0.6 mm, which reaches the 80% tensile strength of the 5083 alloys.

The process of YAG laser welding for 316L stainless steel and 6061 aluminum alloy was investigated, the associated process parameters of laser welding (welding current, laser pulse width, laser frequency and welding speed) were optimized, and the tensile shear strength and microhardness within the weld zone of the 316L/6061 dissimilar matels joint was analyzed. The results show that: the optimized welding current was 100 A, laser pulse width was 4.5 ms, laser frequency was 12 Hz and welding speed was 0.17 m/min; the corresponding joint tensile shear strength was 98.86 MPa; the microhardness of weld pool was between that of the aluminum alloy and stainless steel, and microhardness reduced with diverging from the weld center (from the weld center to the fusion line).

The 1Cr18Ni9Ti stainless steel sheet samples with the thickness of 0.7 mm were welded by laser welding and TIG welding, respectively, and the microstructure and mechanical properties of the weld joints were investigated. It was found that the width of the heat affected zone of laser welding sample was approximately 60 μm, and the microstructure in the weld was dominated by the columnar grains growing epitaxially to the weld bond. The width of the heat affected zone of TIG welding sample was about 1.3mm, and the twin was formed in the heat affected zone. The microstructure in the TIG weld was composed by the epitaxial columnar dendritic grains near the weld bond and the equiaxed dendritic grains in the middle of the weld. The formation mechanism of the microstructure in the laser weld and TIG weld was disclosed based on the columnar to equiaxed transition (CET) model. The microhardness and room temperature tensile testing indicated that the weld hardness obtained by laser welding and TIG welding were all lower than that of the base metal. The hardness distribution curve of the TIG welding sample was like a saddle with the hardness of the heat affected zone lowest. The strength of the laser welding sample is much higher than that of TIG welding sample.

Laser Lap Welding of industrial pure nickel NI201 was studied by using high power Nd:YAG laser and welding robots. The formation and mechanical properties of welded joints was analyzed by optical microscopes, microhardness tester, tensile testing machine, scanning electron microscopy. The influence of welding parameters on the formation and mechanical properties of joints was studied. From the experimental results, it is found that the fine macro-morphology of lap laser welded joint was appeared. Microhardness is different in different zone of laser lap welding joint, the minimum tensile strength of laser lap welding is 389.5 MPa, which is 92% of the base metal. Furthermore, laser power and welding speed has a great influence on macro profile, formation and mechanical properties.

The stainless steel is machined with the picosecond laser, and the morphologyandquality are characterizedby theconfocal microscopy. The effect of laser fluence and feeding speed on the morphologyandquality of micro-holes, and the effect of angle between laser beam and workpiece on taper are studied. The results show that the heat effect and diameter of micro-holes are increasing, and the taper and the circularity at entrance are decreasing as the increasing of the laser fluence. The circularity at exit increases as the laser fluencegrows, then it tends to be stable till the decreasing. The circularity at entrance keeping on 98% and the diameter at entrance aren’t affected by the feeding speed. The diameterat exit decreases as the feeding speed grows, then it tends to be stable.When the feeding speed increases, the conicity increases to 4°, the circularity at exit increases to 97%～98%. At last, the nonlinear correlation between actual conicity and rotation angle of workpiece is demonstrated, and the function is given.

As the large hole taper and large relative aperture error and other problems exist with laser drilling on Al2O3 ceramic, a technology called low-pressure water jet assisted laser drilling of Al2O3 ceramic has been proposed. Through the comparative analysis, it mainly studied the rules of speed of the water jet on the impact of quality of Al2O3 ceramic using low-pressure water jet assisted laser drilling, compared with the direct laser drilling. Experiments proved that, taking advantage of the erosion and cooling of water jet, the composite drilling can greatly reduce the hole taper and relative aperture error, also can reduce molten slags accumulating on material surface and inwall of Al2O3 ceramic, thus improving and rising the quality of drilling on Al2O3 ceramic.

This paper compares the impact of laser direct etching and water jet assisted laser etching on Al2O3-SiC composite ceramics, and discusses the effects of the velocity of water jet on the shape and removal amount of groove. The results show that: The processing method of water jet assisted laser etching can greatly reduce the molten slags of groove, and decrease the thickness of recast layer efficiently, the quality of groove can be improved obviously; Within a given range, the velocity of water jet becomes bigger, the shape of groove becomes more accessible to standard V-groove; When the velocity of water jet increases continuously, the loss of laser energy is more and more, which makes the removal amount of groove become small progressively.

The processing of laser precision cutting quarts glass has been researched, the processing effects influenced by different parameters have been discussed. Use a 1.064 μm picosecond laser as light source, scribe cutting the JGS1-1 quartz glass which thickness is 0.4mm. Under the striping speed 700 mm/s, We get sample which obverse side edge collapse 11.08 μm, back side edge collapse 7.610 μm and side roughness 4um. Combined with the actual machining requirements, the influence of the light source, duty cycle, the point pitch and the focusing spot have been analyzed by using the control variable method and the best parameters have been given.

In this paper, the effect of laser processing parameters on the cutting of glass is studied by changing the laser parameters of the Edge Wave GmbH 532 nm wavelength nanosecond laser. Experiments show that we could get smooth edges, no transverse micro-cracking and free debris of glass substrates with higher yields by optimizing the laser parameters like current values, filling gap sizes, cutting depths and cutting speeds.

Aiming at the problem of real-time weld position detection in seam tracking, a line laser detecting sensor which could abstract 3D data of the seam contour was designed. First, an industrial camera with filter collected image of the laser stripe which was projected on the weld surface by a laser with specific wavelength. Second, the center line of the laser stripe was extracted after image enhancing, binarization, noise filtering and thinning through algorithms of image processing. Third, based on the triangulation method, the 3D coordinates of seam contour were calculated from the pixel coordinates of the center line. At last, two detecting experiments were carried to verify the measurement precision and anti-interference ability respectively. The experimental results indicate that measurement precision can reach ±0.2 mm with good anti-interference ability to arc and spatter, which can satisfy the requirement of welding.

In this paper, we present a diode side-pumped Nd:YAP laser based on TEC temperature controlling that can produce single pulse energy of 12.00 mJ and 11.45 mJ of 1.34 μm output under the flat-flat cavity and flat-concave cavityat at repetition rate of 20 Hz. A BBO crystal was used as E-O Q-switched crystal and there was no polarizer in the resonator. The 38ns pulse width of 1.34 μm was obtained with a repetition rate of 20 Hz under the flat-flat cavity. The output characteristic of 1.08 μm was also experimentally researched and the largest single pulse energy of 28.5 mJ and pulse duration of 27 ns was obtained at a repetition rate of 20 Hz under the same flat-flat cavity.

By using the nanorods and nanosheets bismuthous sulfide materials, we report the successful fabrication of a new type of photodetector by the method widely used for solar cells. The photodetector revealed good properties for laser beam of 1024nm. The photoconductive properties of both samples were also studied by configuring the samples as photodetectors, exhibiting different photosensitivity. The results indicate the nanorods materials have higher photosensitivity than the nanosheets materials. Our results imply that the new type of photodetector is prospective candidate for high-performance photodetector.

To observe the effect of long-pulsed Nd:YAG laser in treating venous lakes. Methods: A 1 064 nm long-pulsed Nd:YAG laser (spot size: 5 mm/7 mm, energy: 90～110 J/cm2, pulse duration: 15～30 ms.) was used to treat the patient’s lesions. The desirable clinical endpoint of the treatment was lesions turned pallor and shrunk immediately after the irradiation. Continuous airflow cooling was always applied during the laser treatment. The treatment interval was at least 2 months. Results: Of the 23 patients, 19 of them were treated in one session, 3 of them were treated in two sessions and 1 of them was treated in three sessions. 15(60.9%) of them got excellent results and 9(39.1%)of them got good results. 5(20.8%)of them got hypopigmentation as the side effects. Conclusions: We conclude that it is simple and efficient in treating venous lakes by long-pulsed Nd:YAG laser.